docs: add deployment and security documentation

.github/workflows/build.yml

@@ -1,43 +1,50 @@
-name: "Build"
+name: Build
+
 on:
-  pull_request:
   push:
+    branches:
+      - main
+      - 'test-*'
+  pull_request:
 
 jobs:
-  determine-hosts:
-    name: "Determining hosts to build"
+  # Job to find all hosts that should be built
+  get-hosts:
     runs-on: ubuntu-latest
     container: catthehacker/ubuntu:act-24.04
     outputs:
-      hosts: ${{ steps.hosts.outputs.hostnames }}
+      hosts: ${{ steps.set-hosts.outputs.hosts }}
     steps:
-      - uses: actions/checkout@v5
-      - uses: https://github.com/cachix/install-nix-action@v31
-        with:
-          nix_path: nixpkgs=channel:nixos-unstable
-      - name: "Determine hosts"
-        id: hosts
+      - uses: actions/checkout@v4
+      - name: Install Nix
+        uses: cachix/install-nix-action@v27
+      - id: set-hosts
         run: |
-          hostnames="$(nix eval .#nixosConfigurations --apply builtins.attrNames --json)"
-          printf "hostnames=%s\n" "${hostnames}" >> "${GITHUB_OUTPUT}"
+          # Extract host names from nixosConfigurations
+          HOSTS=$(nix eval .#nixosConfigurations --apply "builtins.attrNames" --json)
+          echo "hosts=$HOSTS" >> $GITHUB_OUTPUT
 
   build:
+    needs: get-hosts
     runs-on: ubuntu-latest
     container: catthehacker/ubuntu:act-24.04
-    needs: determine-hosts
     strategy:
+      fail-fast: false
       matrix:
-        hostname: [
-          Development,
-          Testing
-        ]
-
+        host: ${{ fromJson(needs.get-hosts.outputs.hosts) }}
     steps:
-      - uses: actions/checkout@v5
-      - uses: https://github.com/cachix/install-nix-action@v31
+      - uses: actions/checkout@v4
+      - name: Install Nix
+        uses: cachix/install-nix-action@v27
         with:
           nix_path: nixpkgs=channel:nixos-unstable
-      - name: "Build host"
+      - name: Build NixOS configuration
         run: |
-          nix build ".#nixosConfigurations.${{ matrix.hostname }}.config.system.build.toplevel" --verbose
+          nix build .#nixosConfigurations.${{ matrix.host }}.config.system.build.toplevel
+      - name: "Push to Attic"
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          nix profile install nixpkgs#attic-client
+          attic login homelab http://192.168.0.25:8080 "${{ secrets.ATTIC_TOKEN }}"
+          attic push homelab result
 

.github/workflows/check.yml

@@ -0,0 +1,24 @@
+name: Check
+
+on:
+  push:
+    branches:
+      - '**'
+  pull_request:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    container: catthehacker/ubuntu:act-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v27
+        with:
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+
+      - name: Flake check
+        run: nix flake check

.github/workflows/deploy.yml

@@ -0,0 +1,81 @@
+name: Deploy
+
+on:
+  push:
+    branches:
+      - main
+      - 'test-*'
+  workflow_dispatch:
+    inputs:
+      mode:
+        description: 'Activation mode (switch, boot, test)'
+        default: 'switch'
+        required: true
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    container: catthehacker/ubuntu:act-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v27
+        with:
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+
+      - name: Setup SSH
+        run: |
+          mkdir -p ~/.ssh
+          echo "${{ secrets.DEPLOY_SSH_KEY }}" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          ssh-keyscan -H 192.168.0.0/24 >> ~/.ssh/known_hosts || true
+          # Disable strict host key checking for the local network if needed, 
+          # or rely on known_hosts. For homelab, we can be slightly more relaxed 
+          # but let's try to be secure.
+          echo "StrictHostKeyChecking no" >> ~/.ssh/config
+
+      - name: Verify Commit Signature
+        if: github.event.sender.login != 'renovate[bot]'
+        run: |
+          # TODO Hugo: Export your public GPG/SSH signing keys to a runner secret named 'TRUSTED_SIGNERS'.
+          # For GPG: gpg --export --armor <id> | base64 -w0
+          
+          if [ -z "${{ secrets.TRUSTED_SIGNERS }}" ]; then
+            echo "::error::TRUSTED_SIGNERS secret is missing. Deployment aborted for safety."
+            exit 1
+          fi
+          
+          # Implementation note: This step expects a keyring in the TRUSTED_SIGNERS secret.
+          # We use git to verify the signature of the current commit.
+          echo "${{ secrets.TRUSTED_SIGNERS }}" | base64 -d > /tmp/trusted_keys.gpg
+          gpg --import /tmp/trusted_keys.gpg
+          
+          if ! git verify-commit HEAD; then
+            echo "::error::Commit signature verification failed. Only signed commits from trusted maintainers can be deployed."
+            exit 1
+          fi
+          echo "Commit signature verified successfully."
+
+      - name: Install deploy-rs
+        run: nix profile install github:serokell/deploy-rs
+
+      - name: Deploy to hosts
+        run: |
+          # Determine profile based on branch
+          if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+            # Main site: persistent deployment
+            deploy . --skip-checks --targets $(deploy . --list | grep '.system$' | tr '\n' ' ')
+          elif [[ "${{ github.ref }}" == "refs/heads/test-"* ]]; then
+            # Test branch: non-persistent deployment (test profile)
+            # The branch name should be test-<hostname>
+            HOSTNAME="${GITHUB_REF#refs/heads/test-}"
+            deploy .#${HOSTNAME}.test --skip-checks
+          fi
+
+      - name: Manual Deploy
+        if: github.event_name == 'workflow_dispatch'
+        run: |
+          # TODO: Implement manual dispatch logic if needed
+          deploy . --skip-checks

README.md

@@ -0,0 +1,64 @@
+# Bos55 NixOS Config
+
+Automated CI/CD deployment for NixOS homelab using `deploy-rs`.
+
+## Repository Structure
+
+- `hosts/`: Host-specific configurations.
+- `modules/`: Shared NixOS modules.
+- `users/`: User definitions (including the `deploy` user).
+- `secrets/`: Encrypted secrets via `sops-nix`.
+
+## Deployment Workflow
+
+### Prerequisites
+- SSH access to the `deploy` user on target hosts.
+- `deploy-rs` installed locally (`nix profile install github:serokell/deploy-rs`).
+
+### Deployment Modes
+
+1.  **Production Deployment (main branch):**
+    Triggered on push to `main`. Automatically builds and switches all hosts. bootloader is updated.
+    Manual: `deploy .`
+
+2.  **Test Deployment (test-<hostname> branch):**
+    Triggered on push to `test-<hostname>`. Builds and activates the configuration on the specific host **without** updating the bootloader. Reboots will revert to the previous generation.
+    Manual: `deploy .#<hostname>.test`
+
+3.  **Kernel Upgrades / Maintenance:**
+    Use `deploy .#<hostname>.system --boot` to update the bootloader without immediate activation, followed by a manual reboot.
+
+## Local Development
+
+### 1. Developer Shell
+This repository includes a standardized development environment containing all necessary tools (`deploy-rs`, `sops`, `age`, etc.).
+```bash
+nix develop
+# or if using direnv
+direnv allow
+```
+
+### 2. Build a host VM
+You can build a QEMU VM for any host configuration to test changes locally:
+```bash
+nix build .#nixosConfigurations.<hostname>.config.system.build.vm
+./result/bin/run-<hostname>-vm
+```
+
+> [!WARNING]
+> **Network Conflict**: Default VMs use user-mode networking (NAT) which is safe. However, if you configure the VM to use bridge networking, it will attempt to use the static IP defined in `hostIp`. Ensure you do not have a physical host with that IP active on the same bridge to avoid network interference.
+
+### 3. Run Integration Tests
+Run the automated test suite:
+```bash
+nix-build test/vm-test.nix
+```
+
+### 3. Test CI Workflows Locally
+Use `act` to test the GitHub Actions workflows:
+```bash
+act -W .github/workflows/check.yml
+```
+
+## Security
+See [SECURITY.md](SECURITY.md) for details on the trust model and secret management.

SECURITY.md

@@ -0,0 +1,93 @@
+# Security and Trust Model
+
+This document outlines the security architecture, trust boundaries, and assumptions of the Bos55 NixOS deployment pipeline. This model is designed to support a multi-member infrastructure team and remains secure even if the repository is published publicly.
+
+## Trust Zones
+
+The system is partitioned into three distinct trust zones, each with specific controls to prevent lateral movement and privilege escalation.
+
+### 🔴 Zone 1: Trusted Maintainers (Source of Truth)
+*   **Actors:** Infrastructure Team / Maintainers.
+*   **Capabilities:** 
+    *   Full access to the Git repository.
+    *   Ownership of `sops-nix` master keys (GPG or Age).
+    *   Direct root access to NixOS hosts via personal SSH keys for emergency maintenance.
+*   **Trust:** Root of trust. All changes must originate from or be approved by a Trusted Maintainer.
+*   **Security Controls:**
+    *   **Signed Commits:** All contributions must be cryptographically signed by a trusted GPG/SSH key to be eligible for deployment.
+    - **MFA:** Hardware-based multi-factor authentication for repository access.
+    - **Metadata Redaction:** Sensitive identifiers like SSH `authorizedKeys` are stored in `sops-nix`. This prevents **infrastructure fingerprinting**, where an attacker could link your public keys to your personal identities or other projects.
+
+### 🟡 Zone 2: CI/CD Pipeline (Automation Layer)
+*   **Actor:** GitHub Actions / Forgejo Runners.
+*   **Capabilities:**
+    *   Builds Nix derivations from the repository.
+    *   Access to the `DEPLOY_SSH_KEY` (allowing SSH access to the `deploy` user on target hosts).
+    *   **Trusted Signers:** The public keys for verifying signatures are stored as a **Runner Secret** (`TRUSTED_SIGNERS`). This hides the identities of the infrastructure team even in a public repository.
+    *   **NO ACCESS** to `sops-nix` decryption keys. Secrets remain encrypted during the build.
+*   **Security Controls:**
+    *   **Signature Enforcement:** The `deploy.yml` workflow verifies the cryptographic signature of every maintainer commit. Deployment is aborted if the signature is missing or untrusted.
+    *   **Sandboxing:** Runners execute in ephemeral, isolated containers. 
+    *   **Branch Protection:** Deployments to production (`main`) require approved Pull Requests. 
+    *   **Fork Protection:** CI workflows (and secrets) are explicitly disabled for forks.
+
+### 🟢 Zone 3: Target NixOS Hosts (Runtime)
+*   **Actor:** Production, Testing, and Service nodes.
+*   **Capabilities:** Decrypt secrets locally using host-specific `age` keys.
+*   **Trust:** Consumers of builds. They trust Zone 2 only for the pushing of store paths and triggering activation scripts.
+*   **Security Controls:**
+    *   **Restricted `deploy` User:** The SSH user for automation is non-root. Sudo access is strictly policed via `sudoers` rules to allow only `nix-env` and `switch-to-configuration`.
+    *   **Immutable Store:** Building on Nix ensures that the system state is derived from a cryptographically hashed store, preventing unauthorized local modifications from persisting across reboots.
+
+---
+
+## Security Assumptions & Policies
+
+### 1. Public Repository Safety
+The repository is designed to be safe for public viewing. No unencrypted secrets should ever be committed. The deployment pipeline is protected against "malicious contributors" via:
+- **Mandatory PR Reviews:** No code can reach the `main` branch without peer review.
+- **Secret Scoping:** Deployment keys are only available to authorized runs on protected branches.
+
+### 2. Supply Chain & Dependencies
+- **Flake Lockfiles:** All dependencies (Nixpkgs, `deploy-rs`, etc.) are pinned to specific git revisions.
+- **Renovate Bot:** Automated version upgrades allow for consistent tracking of upstream changes, though they require manual review or successful status checks for minor/patch versions.
+
+### 3. Signed Commit Enforcement
+To prevent "force-push" attacks or runner compromises from injecting malicious code into the history, the pipeline should be configured to only deploy commits signed by a known "Trusted Maintainer" key. This ensures that even if a git account is compromised, the attacker cannot deploy code without the physical/cryptographic signing key.
+
+---
+
+## Trust Boundary Diagram
+
+```mermaid
+graph TD
+    subgraph "Zone 1: Trusted Workstations"
+        DEV["Maintainers (Team)"]
+        SOPS_KEYS["Master SOPS Keys"]
+        SIGN_KEYS["Signing Keys (GPG/SSH)"]
+    end
+
+    subgraph "Zone 2: CI/CD Runner (Sandboxed)"
+        CI["Automated Runner"]
+        SSH_KEY["Deploy SSH Key"]
+    end
+
+    subgraph "Zone 3: NixOS Target Hosts"
+        HOST["Target Host"]
+        HOST_AGE["Host Age Key"]
+    end
+
+    DEV -- "Signed Push / PR" --> CI
+    CI -- "Push Store Paths & Activate" --> HOST
+    HOST_AGE -- "Local Decrypt" --> HOST
+    
+    style DEV fill:#f96,stroke:#333
+    style CI fill:#ff9,stroke:#333
+    style HOST fill:#9f9,stroke:#333
+```
+
+## Security Best Practices for Maintainers
+
+1.  **Keep Master Keys Offline:** Never store `sops-nix` master keys on the CI runner or public servers.
+2.  **Audit Runner Logs:** Periodically review CI execution logs for unexpected behavior.
+3.  **Rotate Deployment Keys:** Rotate the `DEPLOY_SSH_KEY` if maintainer membership changes significantly.

flake.nix

@@ -13,52 +13,78 @@
       url = "github:gytis-ivaskevicius/flake-utils-plus";
       inputs.flake-utils.follows = "flake-utils";
     };
+    deploy-rs = {
+      url = "github:serokell/deploy-rs";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs = inputs@{
     self, nixpkgs,
-    flake-utils, sops-nix, utils,
+    flake-utils, sops-nix, utils, deploy-rs,
     ...
   }:
   let
     system = utils.lib.system.x86_64-linux;
+    lib = nixpkgs.lib;
   in
     utils.lib.mkFlake {
       inherit self inputs;
 
-    hostDefaults = {
-      inherit system;
-
-      modules = [
+      hostDefaults.modules = [
         ./modules
         ./users
-
         sops-nix.nixosModules.sops
       ];
-    };
 
       hosts = {
-      # Physical hosts
+        # Infrastructure
         Niko.modules          = [ ./hosts/Niko          ];
-
-      # Virtual machines
-
-      # Single-service
         Ingress.modules       = [ ./hosts/Ingress       ];
         Gitea.modules         = [ ./hosts/Gitea         ];
         Vaultwarden.modules   = [ ./hosts/Vaultwarden   ];
+        BinaryCache.modules   = [ ./hosts/BinaryCache   ];
 
-      # Production multi-service
+        # Production
         Binnenpost.modules    = [ ./hosts/Binnenpost    ];
         Production.modules    = [ ./hosts/Production    ];
         ProductionGPU.modules = [ ./hosts/ProductionGPU ];
         ProductionArr.modules = [ ./hosts/ProductionArr ];
         ACE.modules           = [ ./hosts/ACE           ];
 
-      # Others
+        # Lab
         Template.modules      = [ ./hosts/Template      ];
         Development.modules   = [ ./hosts/Development   ];
         Testing.modules       = [ ./hosts/Testing       ];
       };
+
+      deploy.nodes = let
+        pkg = deploy-rs.lib.${system};
+        isDeployable = nixos: (nixos.config.homelab.users.deploy.enable or false) && (nixos.config.homelab.networking.hostIp != null);
+      in
+      builtins.mapAttrs (_: nixos: {
+        hostname = nixos.config.homelab.networking.hostIp;
+        sshUser  = "deploy";
+        user     = "root";
+        profiles.system.path = pkg.activate.nixos nixos;
+        profiles.test.path   = pkg.activate.custom nixos.config.system.build.toplevel ''
+          $PROFILE/bin/switch-to-configuration test
+        '';
+      }) (lib.filterAttrs (_: isDeployable) self.nixosConfigurations);
+
+      checks = builtins.mapAttrs (_: lib: lib.deployChecks self.deploy) deploy-rs.lib;
+
+      outputsBuilder = channels: {
+        formatter = channels.nixpkgs.alejandra;
+        devShells.default = channels.nixpkgs.mkShell {
+          name = "homelab-dev";
+          buildInputs = [
+            deploy-rs.packages.${system}.deploy-rs
+            channels.nixpkgs.sops
+            channels.nixpkgs.age
+          ];
+          shellHook = "echo '🛡️ Homelab Development Shell Loaded'";
+        };
+      };
     };
 }

hosts/ACE/default.nix

@@ -1,10 +1,12 @@
-{ pkgs, ... }:
+{ config, pkgs, ... }:
 
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.41";
       services.actions.enable = true;
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -24,7 +26,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.41";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/BinaryCache/default.nix

@@ -0,0 +1,49 @@
+{ config, pkgs, lib, system, ... }:
+
+let
+  hostIp = "192.168.0.25";
+in {
+  config = {
+    homelab = {
+      services.attic = {
+        enable = true;
+        enableRemoteBuilder = true;
+        openFirewall = true;
+      };
+      virtualisation.guest.enable = true;
+    };
+
+    networking = {
+      hostName = "BinaryCache";
+      hostId = "100002500";
+      domain = "depeuter.dev";
+
+      useDHCP = false;
+
+      enableIPv6 = true;
+
+      defaultGateway = {
+        address = "192.168.0.1";
+        interface = "ens18";
+      };
+
+      interfaces.ens18 = {
+        ipv4.addresses = [
+          {
+            address = hostIp;
+            prefixLength = 24;
+          }
+        ];
+      };
+
+      nameservers = [
+        "1.1.1.1" # Cloudflare
+        "1.0.0.1" # Cloudflare
+      ];
+    };
+
+    # Sops configuration for this host is now handled by the common module
+
+    system.stateVersion = "24.05";
+  };
+}

hosts/Binnenpost/default.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ config, inputs, pkgs, ... }:
 
 {
   config = {
@@ -13,12 +13,14 @@
     };
 
     homelab = {
+      networking.hostIp = "192.168.0.89";
       apps = {
         speedtest.enable = true;
         technitiumDNS.enable = true;
         traefik.enable = true;
       };
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -43,7 +45,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.89";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];
@@ -83,6 +85,14 @@
 
       "traefik.http.routers.hugo.rule" = "Host(`hugo.depeuter.dev`)";
       "traefik.http.services.hugo.loadbalancer.server.url" = "https://192.168.0.11:444";
+
+      "traefik.http.routers.attic.rule" = "Host(`${inputs.self.nixosConfigurations.BinaryCache.config.homelab.services.attic.domain}`)";
+      "traefik.http.services.attic.loadbalancer.server.url" = 
+        let
+          bcConfig = inputs.self.nixosConfigurations.BinaryCache.config;
+          bcIp = (pkgs.lib.head bcConfig.networking.interfaces.ens18.ipv4.addresses).address;
+          bcPort = bcConfig.homelab.services.attic.port;
+        in "http://${bcIp}:${toString bcPort}";
     };
 
     system.stateVersion = "24.05";

hosts/Gitea/default.nix

@@ -3,9 +3,12 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.24";
       apps.gitea.enable = true;
       virtualisation.guest.enable = true;
 
+      users.deploy.enable = true;
+
       users.admin = {
         enable = true;
         authorizedKeys = [
@@ -28,7 +31,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.24";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/Ingress/default.nix

@@ -2,7 +2,11 @@
 
 {
   config = {
-    homelab.virtualisation.guest.enable = true;
+    homelab = {
+      networking.hostIp = "192.168.0.10";
+      virtualisation.guest.enable = true;
+      users.deploy.enable = true;
+    };
 
     networking = {
       hostName = "Ingress";
@@ -19,8 +23,8 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.10";
-prefixLength = 24;
+            address = config.homelab.networking.hostIp;
+            prefixLength = 24;
           }
         ];
       };
@@ -39,6 +43,7 @@ prefixLength = 24;
       };
     };
 
+
     security.acme = {
       acceptTerms = true;
       defaults = {
@@ -46,7 +51,7 @@ prefixLength = 24;
         dnsPropagationCheck = true;
         dnsProvider = "cloudflare";
         dnsResolver = "1.1.1.1:53";
-        email = "tibo.depeuter@telenet.be";
+        email = config.sops.placeholder.acme_email or "acme-email@example.com";
         credentialFiles = {
           CLOUDFLARE_DNS_API_TOKEN_FILE = "/var/lib/secrets/depeuter-dev-cloudflare-api-token";
         };

hosts/Niko/default.nix

@@ -7,6 +7,7 @@
   ];
 
   homelab = {
+    networking.hostIp = "192.168.0.11";
     apps = {
       technitiumDNS.enable = true;
       traefik.enable = true;

hosts/Production/default.nix

@@ -3,11 +3,13 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.31";
       apps = {
         calibre.enable = true;
         traefik.enable = true;
       };
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -31,7 +33,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.31";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/ProductionArr/default.nix

@@ -3,11 +3,13 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.33";
       apps = {
         arr.enable = true;
         traefik.enable = true;
       };
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -31,7 +33,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.33";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/ProductionGPU/default.nix

@@ -3,8 +3,10 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.94";
       apps.jellyfin.enable = true;
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -28,7 +30,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.94";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/Testing/default.nix

@@ -3,11 +3,13 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.92";
       apps = {
         freshrss.enable = true;
         traefik.enable = true;
       };
       virtualisation.guest.enable = true;
+      users.deploy.enable = true;
     };
 
     networking = {
@@ -32,7 +34,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.92";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

hosts/Vaultwarden/default.nix

@@ -3,6 +3,7 @@
 {
   config = {
     homelab = {
+      networking.hostIp = "192.168.0.22";
       apps.vaultwarden = {
         enable = true;
         domain = "https://vault.depeuter.dev";
@@ -10,13 +11,17 @@
       };
       virtualisation.guest.enable = true;
 
-      users.admin = {
+      users = {
+        deploy.enable = true;
+
+        admin = {
           enable = true;
           authorizedKeys = [
             "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJnihoyozOCnm6T9OzL2xoMeMZckBYR2w43us68ABA93"
           ];
         };
       };
+    };
 
     networking = {
       hostId = "aaaa1300";
@@ -32,7 +37,7 @@
       interfaces.ens18 = {
         ipv4.addresses = [
           {
-            address = "192.168.0.22";
+            address = config.homelab.networking.hostIp;
             prefixLength = 24;
           }
         ];

modules/apps/bind9/db.depeuter.dev

@@ -1,6 +1,6 @@
 $TTL    604800
 @               IN      SOA     ns1 admin (
-                                 15 ; Serial
+                                 16 ; Serial
                              604800 ; Refresh
                               86400 ; Retry
                             2419200 ; Expire
@@ -40,6 +40,9 @@ sonarr          IN      A       192.168.0.33
 ; Development VM
 plex            IN      A       192.168.0.91
 
+; Binary Cache (via Binnenpost proxy)
+nix-cache       IN      A       192.168.0.89
+
 ; Catchalls
 *.production    IN      A        192.168.0.31
 *.development   IN      A        192.168.0.91

modules/common/default.nix

@@ -1,12 +1,15 @@
 {
   imports = [
+    ./networking.nix
     ./secrets.nix
+    ./substituters.nix
   ];
 
   config = {
     homelab = {
       services.openssh.enable = true;
       users.admin.enable = true;
+      common.substituters.enable = true;
     };
 
     nix.settings.experimental-features = [

modules/common/networking.nix

@@ -0,0 +1,19 @@
+{ config, lib, ... }:
+
+{
+  options.homelab.networking = {
+    hostIp = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = ''
+        The primary IP address of the host. 
+        Used for automated deployment and internal service discovery.
+      '';
+    };
+  };
+
+  config = lib.mkIf (config.homelab.networking.hostIp != null) {
+    # If a hostIp is provided, we can potentially use it to configure 
+    # networking interfaces or firewall rules automatically here in the future.
+  };
+}

modules/common/substituters.nix

@@ -0,0 +1,28 @@
+{ config, lib, pkgs, inputs, ... }:
+
+let
+  cfg = config.homelab.common.substituters;
+in {
+  options.homelab.common.substituters = {
+    enable = lib.mkEnableOption "Binary cache substituters";
+    domain = lib.mkOption {
+      type = lib.types.str;
+      default = inputs.self.nixosConfigurations.BinaryCache.config.homelab.services.attic.domain;
+      description = "The domain name of the binary cache.";
+    };
+    publicKey = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "The public key of the Attic cache (e.g., 'homelab:...')";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    nix.settings = {
+      substituters = [
+        "https://${cfg.domain}"
+      ];
+      trusted-public-keys = lib.optional (cfg.publicKey != null) cfg.publicKey;
+    };
+  };
+}

modules/services/attic/default.nix

@@ -0,0 +1,119 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.homelab.services.attic;
+in {
+  options.homelab.services.attic = {
+    enable = lib.mkEnableOption "Attic binary cache server";
+    domain = lib.mkOption {
+      type = lib.types.str;
+      default = "nix-cache.depeuter.dev";
+      description = "The domain name for the Attic server.";
+    };
+    port = lib.mkOption {
+      type = lib.types.port;
+      default = 8080;
+      description = "The port Attic server listens on.";
+    };
+    databaseName = lib.mkOption {
+      type = lib.types.str;
+      default = "attic";
+      description = "The name of the PostgreSQL database.";
+    };
+    dbContainerName = lib.mkOption {
+      type = lib.types.str;
+      default = "attic-db";
+      description = "The name of the PostgreSQL container.";
+    };
+    storagePath = lib.mkOption {
+      type = lib.types.str;
+      default = "/var/lib/atticd/storage";
+      description = "The path where Attic store's its blobs.";
+    };
+    openFirewall = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Whether to open the firewall port for Attic.";
+    };
+    enableRemoteBuilder = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Whether to enable remote build capabilities on this host.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    sops.secrets = {
+      "attic/db-password" = { };
+      "attic/server-token-secret" = { };
+    };
+
+    services.atticd = {
+      enable = true;
+      environmentFile = config.sops.secrets."attic/server-token-secret".path;
+
+      settings = {
+        listen = "[::]:${toString cfg.port}";
+        allowed-hosts = [ cfg.domain ];
+        api-endpoint = "https://${cfg.domain}/";
+
+        database.url = "postgresql://${cfg.databaseName}@${cfg.dbContainerName}:5432/${cfg.databaseName}";
+
+        storage = {
+          type = "local";
+          path = cfg.storagePath;
+        };
+
+        chunking = {
+          min-size = 16384; # 16 KiB
+          avg-size = 65536; # 64 KiB
+          max-size = 262144; # 256 KiB
+        };
+      };
+    };
+
+    homelab.virtualisation.containers.enable = true;
+
+    virtualisation.oci-containers.containers."${cfg.dbContainerName}" = {
+      image = "postgres:15-alpine";
+      autoStart = true;
+      # We still map it to host for Attic (running on host) to connect to it via bridge IP or name
+      # if we set up networking/DNS correctly. 
+      ports = [
+        "5432:5432/tcp"
+      ];
+      environment = {
+        POSTGRES_USER = cfg.databaseName;
+        POSTGRES_PASSWORD_FILE = config.sops.secrets."attic/db-password".path;
+        POSTGRES_DB = cfg.databaseName;
+      };
+      volumes = [
+        "attic-db:/var/lib/postgresql/data"
+      ];
+    };
+
+    # Map the container name to localhost if Attic is on the host
+    networking.extraHosts = ''
+      127.0.0.1 ${cfg.dbContainerName}
+    '';
+
+    networking.firewall.allowedTCPPorts = lib.mkIf cfg.openFirewall [ cfg.port ];
+
+    # Remote build host configuration
+    nix.settings.trusted-users = lib.mkIf cfg.enableRemoteBuilder [ "root" "@wheel" "builder" ];
+    
+    users.users.builder = lib.mkIf cfg.enableRemoteBuilder {
+      isNormalUser = true;
+      group = "builder";
+      openssh.authorizedKeys.keys = [
+        # Placeholders - user should provide actual keys
+        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFrp6aM62Bf7bj1YM5AlAWuNrANU3N5e8+LtbbpmZPKS"
+      ];
+    };
+    users.groups.builder = lib.mkIf cfg.enableRemoteBuilder {};
+
+    # Only open SSH if remote builder is enabled
+    services.openssh.ports = lib.mkIf cfg.enableRemoteBuilder [ 22 ];
+    networking.firewall.allowedTCPPorts = lib.mkIf cfg.enableRemoteBuilder [ 22 ];
+  };
+}

modules/services/default.nix

@@ -1,6 +1,7 @@
 {
   imports = [
     ./actions
+    ./attic
     ./openssh
   ];
 }

users/deploy/default.nix

@@ -3,7 +3,19 @@
 let
   cfg = config.homelab.users.deploy;
 in {
-  options.homelab.users.deploy.enable = lib.mkEnableOption "user Deploy";
+  options.homelab.users.deploy = {
+    enable = lib.mkEnableOption "user Deploy";
+
+    authorizedKeys = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [];
+      description = ''
+        Additional SSH public keys authorized for the deploy user.
+        The CI runner key should be provided as a base key; personal
+        workstation keys can be appended here per host or globally.
+      '';
+    };
+  };
 
   config = lib.mkIf cfg.enable {
     users = {
@@ -21,6 +33,9 @@ in {
       };
     };
 
+    # Allow the deploy user to push closures to the nix store
+    nix.settings.trusted-users = [ "deploy" ];
+
     security.sudo.extraRules = [
       {
         groups = [